Not play on the ground哪错了?

Not play on the ground哪错了? on the play ground 中文 on the play ground 还是 in the play ground Tom and Jack play games on the ground.同义句 Look!He _____(play) foootball on the ground now. There are two _______ students on the play ground There are students on the play ground.改错 I was on the play ground a moment ago. Play on the ground改完否定句 -----（not play) on the road My puppet on the ground.哪里错了? I see some boys( )(play)on the play ground all the time